In many chemical processes and in many other environments vessels are utilized for holding and subsequently discharging loose bulk material. Such vessels commonly comprise a cylindrical body portion with a funnel-shaped discharge at the bottom. There often are problems in providing a uniform efficient discharge of loose bulk material from the vessel because of this funnelling, therefore it is common procedure to provide a discharge facilitating device such as a vibrator. While most material can be suitably discharged in this manner, there still arise situations where the bulk material will have a tendency to hang-up and block the bulk material outlet, rendering the vessel ineffective to perform its desired function.
In the production of pulp from cellulosic chips material, it has been found desirable to steam the cellulosic chips while directly in the chips bin. The chips bin comprises a structure generally as described above, having a main body portion with a conical discharge extending from the body portion. When steaming is practiced within the bin the possibility of the chips clogging up the outlet are greatly enhanced and even with utilization of a vibrating device blockage of the chips outlet can occur. The wet chips have a tendency to adhere to each other and when they are forced to funnel down for discharge there is no place for the chips to go and compaction and blocking thus can ensue.
According to the present invention the problem of hang-up of loose bulk material in a holding and discharge vessel in general, and particularly the hang-up of wet chips in a chips bin with chips bin steaming, is solved in a simple and inexpensive manner. According to the present invention a plurality of spaced void volumes are formed in the material flowing downwardly adjacent the intersection between the main body of the vessel and the conical discharge. The void volumes provide a volume into which material can move as it is being funnelled downwardly, and resulting compaction, hang-up, and blockage of the material outlet are avoided.
The formation of void volumes in the desired manner according to the present invention is preferably accomplished by providing two or more prismatic elements attached to the interior side walls of the main vessel body and extending substantially vertically at least a portion of the length of the vessel body and terminating at generally the bottom of the main vessel body. Typically the prismatic element would be hollow triangular prisms each having the base thereof fixed (e.g., by welding) to the interior of the main vessel body along the length of the base. The prismatic elements preferably extend radially inwardly from the side walls a distance greater than the radial spacing of the interior of the discharge portion bottom from the side walls, although exact dimensions, spacings, shapes, and the like can be varied widely depending upon the particular situation. The utilization of such prismatic elements allows existing vessels to be readily retrofit, although for structures newly fabricated other techniques may be utilized to effect the void volume formation.
It is the primary object of the present invention to prevent blockage of the material outlet in vessels for holding and discharging loose bulk material, and particularly in chips bins wherein steaming is practiced. This and other objects of the invention will become clear from a detailed description of the invention and from the appended claims.